Here we stress a crucial difference between our problem and problems on optimising flows and throughput in typical capacitated communication networks [1]}, [2]}.
In traditional communication networks, the capacity is usually independent in the two directions of the link [3]}.
In our case, however, the amount of packets \(u\)  sends to \(v\)  in a link \((u,v)\)  directly affects \(v\) 's capability to send packets, as each packet \(u\)  send to \(v\)  increases \(v\) 's capacity on \((u,v)\) .
